Dundee Precious Metals adds to their digital transformation with Metso optimizers

The partnership between Dundee Precious Metals and Metso has been a journey towards digital transformation, showcased in previous cases together such as  Courier® 6G SL analyzer and the success story with Geminex™ metallurgical digital twin. Metso's integral role in this journey is evident at two Dundee Precious Metals sites, Ada Tepe and Chelopech, where substantial progress in performance has been made due to the implementation of Metso’s digital solutions.

“We have gone through a digital revolution together with Dundee Precious Metals,” says Jari Moilanen, Director, Digital Solutions, Metso. “We have built the infrastructure and have implemented our ways in which we automate and optimize the unit operations of the plant - and we are seeing results.”

A key player in their upgraded processes has been the utilization of Metso Optimizers. The duty of optimizers is to control key variables of processes and enhance overall plant performance. For the Ada Tepe and Chelopech sites, this applies to grinding, flotation, thickening and now filtration.

"Our aims were smarter processes and informed decisions," says Desislava Sabeva, Chief Metallurgist,  Dundee Precious Metals Chelopech. "Metso's expertise was crucial in achieving our operational targets."

Inspired by the success in Africa, Dundee Precious Metals reached out to Metso to see if our optimizers would work at their mining sites in Bulgaria, namely Ada Tepe (an open-pit gold mine) and Chelopech (an underground copper mine). Metso orchestrated workshops to audit the instrumentation and infrastructure to prepare both sites for seamless optimizer integration.

“The importance of optimizers cannot be understated, since they compensate for the variations that are coming from inputs to the process,” explains Moilanen. “Optimizers perform quick and time-consuming actions in a way that would be challenging for humans to replicate. So, optimizers are working with unit processes such as grinding, flotation, dewatering, thickening or filtration, and helping them adapt to the variability and run the process at given set points.”

Optimizers: the key solution in tackling everyday mining challenges

In today's mining landscape, sites around the world are facing challenges with ore production and variability. Varying ore types means differences in mineral hardness, metal content, complexity and more, proving difficult when extracting valuable minerals. Another hurdle that operations are hoping to overcome is equipment issues, which can lead to certain circuits being bypassed and thus recalibrated.

When dealing with harder ores, achieving fine particle size through grinding becomes time-consuming. This is where the Grinding optimizer comes in, regulating input to maximize capacity and stabilize grind size—an imperative in ore processing.

When it comes to flotation, mineral content complexity directly impacts the recovery of valuable minerals. Since recovery is a key performance indicator for the entire plant, operations are looking to maximize this without sacrificing concentrate quality, and that is the primary duty of the Flotation optimizer.

For thickeners, the separation of solid particles and water is critical, especially since after flotation, those are together in the form of slurry. This task can prove difficult if the particle size distribution or mineral characteristics are varying, as this directly leads to fluctuating results. To combat the challenge, Thickener optimizers play a vital role in managing key variables like underflow density, overflow solids content, and inventory levels, hence the process is as stable as possible despite changing inputs.

Filters present a dual challenge: capacity constraints and moisture content control. Filtration could be the bottleneck of a production, so it is crucial that filter capacity is optimized in these cases. Filter optimizers tackle this challenge by proactively adjusting parameters for stabilized capacity and moisture levels, which is also necessary for transport feasibility.

"For instance, excess moisture in concentrate affects transport options; a ship might refuse overly wet cargo, or you can get penalized on payability for having higher moisture for certain material" explains Moilanen, highlighting the necessity for moisture limits.

Optimizers in action: maximized recovery, minimized losses

As of 2024, both Ada Tepe and Chelopech harness Metso's Grinding, Flotation, Thickener, and Filter optimizers, alongside Geminex™ and Courier® 6G SL analyzer.

With correspondence and check-ins continuing on a regular basis, the Metso team works together with Dundee Precious Metals to ensure each optimizer is reaching its fullest potential.

"Our optimizer projects went extremely well as it successfully met the production expectations, and this was a direct result of the workshop and roadmap planning," notes Jari. "Continuing customer collaboration provides us all with valuable insight so we can focus our efforts where most needed."

Grinding optimizer

At Ada Tepe, achieving precise size distribution for flotation was critical for throughput and specific power targets.

"Before the optimizers, we had difficulties reaching our target consistently," explains Sabeva. "Currently, we maintain target PSD levels around 90% of the time, significantly enhancing our flotation section."

If the PSD is too high, recovery of gold is compromised. Since gold is very fine, it must be liberated to recover. With the Grinding optimizer, Ada Tepe was able to control the rougher section as it became more stable. This new control led to improved downstream performance as the stable flow from rougher to cleaner sections supported efficient recovery.

Flotation optimizer

For both sites, such as in the bulk section in Chelopech and rougher section in Ada Tepe, the aim was to prioritize maximum recovery to minimize losses. With recovery and final concentrate grade as the main KPI’s for the flotation section, it was paramount that this process enables efficiency. Once the flotation optimizer was implemented, this KPI was reached and has continued to make improvements in this area.

"Stabilizing feed flow has significantly impacted final results, especially with the sensitive column machines at Ada Tepe," Sabeva highlights. "Even in Chelopech, the optimizer reacts very logically in flotation, and when we have more smooth and stable feed, the results are very good."

Thickener optimizer

“The thickener optimizer works very well, especially in Ada Tepe,” says Sabeva. “In Chelopech as well, we have definitely seen improvements, such as in the copper thickener, there has been a decrease of flocculant consumption with more stable underflow density.”

A huge benefit of optimizers is the reduced physical operator time. Not only does it streamline manual work by leveraging Metso's Advanced Control Tools platform, but the Thickener optimizer also adjusts underflow pumping rate and flocculant dosage based on process measurements, ensuring stability.

In thickeners, if a parameter changes, an operator’s response could be 4 or 10 hours, and many things may have already happened in that time. The reality is – manual operators cannot match this. The timely, accurate responses of the optimizer prevent sub-optimization and significantly improve thickener operations.

Operator adoption: embracing new technology

Adopting new technologies and adapting to new work methodologies can be daunting. In today’s rapidly evolving landscape, such transitions are becoming increasingly common. Thankfully, operators found Metso optimizers remarkably user-friendly, and recognized their substantial value. Metso optimizers are intuitively designed with minimal buttons, requiring operators to specify their preferences while leaving the optimization process to the system.

“Everyone responds to new technologies differently, but I was impressed that after commissioning, once the operator saw how the system can help them, they actually wanted to use it,” notes Sabeva.

Standardizing operations across shifts emerged as a primary goal at both sites. Differing operator approaches can lead to inconsistencies, consequently impacting performance and safety. By utilizing optimizers, Dundee Precious Metals observed enhanced results and performances since end-of-shift explanations for variation in targets, recoveries, and other KPIs essentially became obsolete.

“Though our operators have many years of experience, I noted something interesting,” says Sabeva. “I noticed that they were still learning from the optimizer. For example, if the operator was told that the target is outside the limit for any reason, they did some kind of action. But they are focusing on that parameter only. Now, since the system looks at the entire unit process, they can see how the system reacts to reach the targets without disturbing the process.”

When implementing an optimizer, operators are trained to use the main functionality. Metso experts provided advanced training to Dundee personnel, delving into optimizer logic and its various workings.

“Our training program includes all the necessary steps and responses for targeting a thickener underflow density of 55% or shifting to 60%,” says Moilanen. “In cases where process inputs or measurements are unavailable, operators are trained to know what their options are in each situation.

Despite COVID-related challenges hindering training and commissioning, Metso found a way to connect and adapt by conducting remote sessions. Leveraging internet-based tools similar to the Geminex operator training system, experts facilitated learning and fine-tuning online.

The transition to digital solutions and optimizer-driven automation has lessened the impact of operator-related disruptions. This shift towards minimized human intervention has notably stabilized processes, resulting in improved recovery rates.

Proficiency and approachability for continued success

Metso recognizes the strength in partnerships. With multiple success stories coming out of our shared history, this continued partnership with Dundee Precious Metals has proven to yield positive results.

“I am very happy that I was involved in these projects, because it’s very easy to work with clever people,” says Sabeva. “I appreciate the experience of Metso team and the Dundee Precious Metals team, and when both work together, great things happen. It is a pleasure to work with Metso.”

Operations want to work with people who are experts in their field, are available when they need them, and above all else – good people who are easy to deal with. Both companies acknowledge this shared value, utilizing the partnership as an opportunity for mutual learning and growth.

“This project is constantly being used as an example of how each project should go,” says Moilanen. “Not only do we hear from the customer that it is easy to deal with us and things go well, but we also hear from our own team how it has gone incredibly smoothly.”

Regular meetings continue even up to this day, further signifying ongoing commitment. Both Metso and Dundee Precious Metals teams engage in continual reviews, exploring avenues for future enhancements and optimization. Working together is one of Metso's core values, and has proved instrumental in this project's success. These efforts ensure a deep understanding of customer needs, allowing prompt adjustments to meet and exceed expectations when needed.

Positive partnering for the planet

Sustainability is at the forefront of industry conversation, and for good reason. Thankfully, both companies share a deep commitment to this critical aspect. Dundee Precious Metals actively pursues sustainability in its operations, exemplified by Chelopech boasting one of the lowest greenhouse gas emissions intensity rates globally among gold mines and maintaining zero discharge of industrial wastewater for consecutive years. Meanwhile, Ada Tepe has pioneered Europe's first Integrated Mine Waste Facility, revolutionizing tailings management to minimize the mine's environmental footprint. With this alignment in environmental values and objectives, it is evident why Dundee Precious Metals and Metso are consistently achieving high performance together.

By integrating Metso's diverse digital solutions—such as Courier 6G, Geminex™ metallurgical digital twin, Optimizers and more—Dundee Precious Metals are getting more out of their process with less, thus enabling more profitable, efficient and sustainable production.

A stable and optimized process not only enhances energy efficiency, but water efficiency as well. Jari highlights the pivotal role of water circuits in flotation performance, stressing the impact of process optimization on sustainable practices.

“In many operations, water circuits are getting closed, so the sites cannot take any more or new water into the process and discharge it back into nature,” says Moilanen. “But the same water does need to be circulated. If this is not done right, flotation performance will get worse. This is where sites can greatly benefit in production and sustainability by optimizing this system.”

Our collective objective remains the optimization of precious resources while curbing environmental impact. The utilization of optimizers in Dundee Precious Metals' grinding, thickening, flotation, and filtration processes have ensured maximum efficiency, so equipment is being used to its fullest potential. Building on the numerous successes together, Dundee Precious Metals and Metso will continue to collaborate and further optimize operations with the latest innovative solutions, thus continuing their path to digitalization. That’s why, together, we are the partner for positive change.